Show YOURSELF by WILFRED T GRENFELL md and YOUR BODY SENTINEL NUMBER THREE the ear I 1 ll 11 b F IL 0 N 46 TC T C I 1 vit ga MA mn b outer ear middle ear inner ear balancing Is like playing ball whichever call catches the ba 11 sends a message to the brain 1 I i ahe third great control Is the v ear the ear la Is a double conj trot it first enables the body to balance and second it acts as a very valuable alarm because while the eyes guard right ahead only the ears guard in two directions ions horses can move their ears around in any direction and can therefore tell better than we can how far off and from what direction the sound Is because the ear car muscles can put the ears tit at the angle that gets the sound I iest best est horses rely much more on their ears than their eyes so do h and leer deer I 1 fortunately as our ears cars are on opposite sides of our head it takes sound waves longer to get to one ear car than the other and that helps us to toll tell how far off the sound Is and which direction it comes from our heating healing machine has on the outside a halthorn halt half horn to collect sound waves and send them down the hole into a tube as the receiver of a telephone does tor for our voice waves the tube Is located in solid bone and away down it so as to be sate safe a drum hend head Is stretched right across the tube in the tube al hairs and wax was to catch and keep out enemies and dirt the drum head Is built up of very fine strings stretching from the alie side of the tube and fastened in the middle to a tiny bone rod called the hummer hammer handle because there Is a knob on the top end of it the handle Is not exactly in the middle so that all the strings are of different lengths and each fiber will start to move in answer to a different note the fact Is our ears can tell us of any note made up of wives waves that measure anywhere between 40 and vibrations to a second now we must have air on both sides of the delicate drum or it would be pressed hat flat by the weight of tile the air outside so the other side of the drum head Is a fine little room called the I 1 middle ear there Is a door in the back wall of this room leading to a pipe the other oilier end of which opens into the big air chamber inside the back of the throat it if you shut your mouth and hold your nose and swallow you will hear bear at air ir crinkle inside your eur ear against the inside of the drum nig big tonsils are apt to block up the inner end of this pipe or when you get a bad cold it sets gets blocked then you can hardly hear anything bec because aue the drum gets pressed in and cant vibrate the arrangement to carry rry the hound bound vibrations across this necessary room Is really marvelous a beautiful necklace of little bones joined to the hend head of the hammer bone is a tiny called the anvil because of its shape and fast to that Is the stirrup bone lct the flat part or plunger of which Is fastened square over the second drum a thin membrane covering in an oval window on the inside wall like this when there Is a lotse the outside drum moves with the sound and the little chain prevents the waves from pulling the inner drum too hard the other side of th the 3 oval window Is the secret chamber called the inner ear this Is beautifully lined and divided into two halls balls each full of watery lymph the front hall leads to the music rown rondii this Is a long tubular corridor which winds round and round an upright hollow pillar getting smaller as it goes up like the enter center piece of tills this conch ishell see picture theres a bone shell shelf half way up the side of the corridor running round the central rud aad so BO many thousands of fibers are stretched from it to the outer wall that it makes a fine curtain the strings getting shorter and shorter us as you go 90 up tip exactly as fiddle strings or harp strings get shorter to in make ake higher and higher notes so these do to receive and answer to higher and higher notes A i ical ell only a single cell thick covers over the outer part of this ns as you see fee in the picture and in this queer passage formed beneath Is the real hearing organ this organ Is made of a few special eel cells I 1 s and runs rung the lie whole way UR up the corridor from bottom to top inside the central column run thousands of wires to central the whole li 9 called the hearing nerve exactly like the seeing perve one fiber runs out over the bony shelf to every single cell on the hearing organ the oval window covered by the plunger of the stirrup la Is in the upper half of the corridor there Is a large round window in the lower halt half covered by an elastic membrane exactly like the eskimos use elastic seal bowel skin to cover their windows because they have no glass in the hearing organ you see the rows of sensitive cells each with flue fine hairs in it and close over them Is a special roof mado made up mostly of live wires that Is of nerves to a cell mass or ganglion thousands of which are lodged lodge on the circular shelf and are local centers sending lending the messages through the hearing bearing wires to central when the outside drum Is moved by a sound wave the plunger of the stirrup presses the water in the top of the corridor down on the tips of the hairs and that pu pushes pubes bes out the elastic clastic round window below the elasticity pulls it back and so it Is just as if the hairs ticked the live wires just tile the right number of times for each note and so wired a hearing picture tit up to central where it Is exactly ns as in the eye immediately preserved in the record chamber called memory as well as interpreted and acted upon by you and roe me there are little specks floating in the corridors also and when stirred up they may help to send up tip messages also these records are so well kept that recently a man listening in on a radio discovered dili covered his lost brother whose voice lie he had not heard for years now lets go back to the other or inner end of tho the hall here la Is another room with live five doors each leading into a big bony tube each Is half a circle so they are called semicircular canals here in this cham her which Is also filled with fluid are again ninny many small specks and also a number of cells with hairs the canals lie ile in the shapes of u big bows at right angles to one another so that one Is flown down when the other is up whichever way your head moves and into them also the fluid goes there Is a row of wires that goes to this room also but it does not come from central front office this time but from the back bach nr ir lower brain office and it Is these canals which enable us to balance see picture when they move too much in certain ways they get troubled and we get giddy some think the specks lodge now on this side now on that of the hairs iii ai they move about and the changing of 0 the weight makes pictures in the lower loer bruin spa sea sickness Is probable a trouble of these balancing canals when the ship shakes us up too much we dont yet exactly understand how any of these pictures are interpreted by the man inside perhaps we never shall iut but the hie and the design are to so wonderful and are r F so care carefully full y protected that we ought il ta know nil lill we can about them Z by the bell syndicate Soil cM ino inc |